[Malvern] Condiments of the Seasoning.

[Geoff Bagley]

Chris Eilbeck wrote:

>Use Gnuplot.
>  
>
<snip>

>Gnuplot is fab.  I use it a lot.
>
>Enjoy!
>
>Chris
>  
>
Hi Chris.
Have a look at my dowsing response to an underground stream.

f(x) = abs( exp(-x*x/2) * cos(x) * cos(5*x) )

The "abs"  reflects the fact that I only perceive magnitude, and not 
polarity (I have tested this).
The exp term  closely resembles the overall envelope.
The two cosine functions are the two periodic components one coarse, one 
fine.

This bit is bizarre -  I can disable the fine periodicity by closing my 
left eye !
You then get a broad central lobe and two small sidelobes separated by 
first order zeroes.
When the fine pattern is present, these two zeroes become second order 
(more rounded). The other four are sharp cusps.

As you will appreciate, all the magnitudes are guestimated - I have no 
way to measure them yet, but I am satisfied
that the three terms in the product are indeed multiplicative (evident 
from the increased order of the zeroes).

Geoff.


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